Retrofit heat pump water heating systems

Abstract

A retrofit heat pump system for a water heater is disclosed. The heat pump system includes a plurality of evaporators to increase the efficiency of heat exchange for the system. The system can also include a plurality of condenser circuits used to heat the water of an existing water tank. A fan disposed in a housing of the heat pump system can draw air across the plurality of evaporators and exhaust cool air external to the heat pump system. The cool air can be exhausted into duct work associated with an air conditioning system of the home. The disclosure also describes a refrigerant distributor for providing uniform liquid refrigerant to the plurality of evaporators.

What is claimed is: 
     
       1. A heat pump system for a water heater comprising:
 a compressor; 
 an evaporator subsystem comprising a first evaporator and a second evaporator; 
 a condenser subsystem proximate a tank of the water heater, the condenser subsystem comprising a first condenser circuit and a second condenser circuit proximate the tank of the water heater, the first condenser circuit and the second condenser circuit being configured to (a) operate simultaneously and (b) receive refrigerant from the compressor; 
 an exhaust fan; and 
 a refrigerant conduit comprising:
 a first flow path extending downstream from the first evaporator; 
 a second flow path extending downstream from the second evaporator; and 
 a third flow path converging from the first flow path and the second flow path and extending to the compressor. 
 
 
     
     
       2. The heat pump system of  claim 1 , wherein the first condenser circuit and the second condenser circuit are disposed within the tank. 
     
     
       3. The heat pump system of  claim 1 , wherein the first condenser circuit and the second condenser circuit are disposed on an outer surface of the tank and are coiled around the tank. 
     
     
       4. The heat pump system of  claim 1 , wherein the heat pump system operates at 120V and does not comprise a heating element. 
     
     
       5. The heat pump system of  claim 1 , further comprising:
 a housing; and 
 a fan disposed between the first evaporator and the second evaporator. 
 
     
     
       6. The heat pump system of  claim 5 , wherein the fan is configured to exhaust air (i) from around the first evaporator and the second evaporator and (ii) to a ventilation conduit associated with either an air conditioning system or a gas exhaust vent. 
     
     
       7. The heat pump system of  claim 1 , wherein:
 the first evaporator comprises a first coil network and a second coil network; 
 the second evaporator comprises a third coil network and a fourth coil network; and 
 the heat pump system further comprises:
 an expansion valve; and 
 a refrigerant distributor comprising a first end in fluid communication with the expansion valve and a second end comprising four distribution conduits, each distribution conduit of the four distribution conduits in fluid communication with one of the first coil network, the second coil network, the third coil network, or the fourth coil network. 
 
 
     
     
       8. The heat pump system of  claim 7 , wherein the refrigerant distributor comprises a hollow interior cavity configured to pool refrigerant from the expansion valve before the refrigerant exits the four distribution conduits. 
     
     
       9. A retrofit heat pump for a water heater comprising:
 a housing attachable to the water heater; 
 a plurality of evaporators disposed within the housing; 
 a compressor in fluid communication with the plurality of evaporators; 
 a plurality of condenser circuits disposed proximate a tank of the water heater, the plurality of condenser circuits comprising a first condenser circuit and a second condenser circuit, the first condenser circuit and the second condenser circuit being configured to (a) operate simultaneously and (b) receive refrigerant from the compressor; and 
 an expansion valve comprising a first end in fluid communication with the plurality of condenser circuits and a second end in fluid communication with the plurality of evaporators. 
 
     
     
       10. The retrofit heat pump of  claim 9 , wherein the plurality of condenser circuits is disposed within the tank. 
     
     
       11. The retrofit heat pump of  claim 9 , wherein the plurality of condenser circuits is disposed on an outer surface of the tank and is coiled around the tank. 
     
     
       12. The retrofit heat pump of  claim 9 , wherein the retrofit heat pump operates at 120V and does not comprise a heating element. 
     
     
       13. The retrofit heat pump of  claim 9 , wherein:
 the plurality of evaporators comprises a first evaporator and a second evaporator; 
 the first evaporator comprises a first coil network and a second coil network; 
 the second evaporator comprises a third coil network and a fourth coil network; and 
 the retrofit heat pump further comprises a refrigerant distributor disposed between the expansion valve and the first and second evaporators, the refrigerant distributor comprising a first end in fluid communication with the expansion valve and a second end comprising four distribution conduits, each distribution conduit of the four distribution conduits in fluid communication with one of the first coil network, the second coil network, the third coil network, or the fourth coil network. 
 
     
     
       14. The retrofit heat pump of  claim 9 , further comprising a fan disposed within the housing and between a first evaporator and a second evaporator of the plurality of evaporators. 
     
     
       15. The retrofit heat pump of  claim 14 , wherein the fan is configured to exhaust air from around the plurality of evaporators and to a ventilation conduit associated with either an air conditioning system or a gas exhaust vent. 
     
     
       16. A hybrid water heater system comprising:
 a water heater comprising a tank; and 
 a heat pump system attachable to the water heater and comprising:
 an evaporator subsystem comprising a first evaporator and a second evaporator; 
 a compressor in fluid communication with the evaporator subsystem; and 
 a condenser subsystem comprising a first condenser circuit and a second condenser circuit, the first condenser circuit and second condenser circuit being positioned proximate the tank, the first condenser circuit and the second condenser circuit being configured to (a) operate simultaneously and (b) receive refrigerant from the compressor. 
 
 
     
     
       17. The hybrid water heater system of  claim 16 , wherein:
 the first condenser circuit and the second condenser circuit are disposed on an outer surface of, and are coiled around, the tank; and 
 the hybrid water heater system further comprises an insulative housing enclosing the first condenser circuit and the second condenser circuit. 
 
     
     
       18. The hybrid water heater system of  claim 16 , wherein:
 the water heater and the heat pump system are configured to be powered by different power supplies; and 
 the heat pump system comprises an electrical connection configured to connect to and receive power from a 120V power outlet. 
 
     
     
       19. The hybrid water heater system of  claim 16 , wherein:
 the water heater is a gas water heater comprising an exhaust vent; and 
 the heat pump system comprises a fan positioned between the first evaporator and the second evaporator and coaxial with the exhaust vent. 
 
     
     
       20. The hybrid water heater system of  claim 16 , wherein:
 the first evaporator comprises a first coil network and a second coil network; 
 the second evaporator comprises a third coil network and a fourth coil network; and 
 the heat pump system further comprises:
 an expansion valve; and 
 a refrigerant distributor comprising a first end in fluid communication with the expansion valve and a second end comprising four outlets, each outlet of the four outlets in fluid communication with one of the first coil network, the second coil network, the third coil network, or the fourth coil network.